Hypodermic syringe



May 25, 1954 M. J. COHEN y 2,679,246

HYPODERMIC SYRINGE Filed July 22, 1952 'Ff-9,5 3|' -BY y M ATTORNEYPatented May 25, 1954 HYPODERMIC SYRINGE Milton J. Cohen, Washington, D.C., assignor to Miljam Instrument Corporation, Washington, D. C., acorporation of Delaware Application July 22, 1952, Serial No. 300,193

(Cl. 12S-218) 9 Claims.

My invention relates to a hypodermic syringe, and some objects of thesame are to provide a syringe that shall consist of few and simpleparts, that shall be capable of being assembled quickly and easily, thatshall provide means for storing a medicament for extended periods insafety, and that shall be capable of being put into condition for usewith the greatest of ease when needed, while also being capable ofinimediate use for making a complete and proper injection quickly and byunskilled persons or by persons acting under conditions of stress, as intimes of public calamity or under battle conditions.

Another object is to provide a novel plunger for a syringe.

Another object is to provide means for sealing the needle of ahypod-ermic syringe so as to prevent any loss of medicament, as byleakage or seeping due to change of air pressure or for any otherreason.

Another object is to provide rubber articles of diiierent hardness andelasticity in diierent parts of the same.

Still another object is to provide convenient and readily accessiblemeans for sterilizing an area of skin preliminary to injection, as isapproved practice in all surgery and dentistry, wherever such antisepsisis possible.

Referring now to the annexed drawings, which are made a part of thisapplication and in which similar reference characters indicate similarparts:

Fig. 1 is an elevation, partly in section, of the improved syringe inthe form at present preferred.

Fig. 2, a similar view, with parts in a diierent position,

Fig. 3, a like view of a modified form of the invention,

Fig. 4, a view like Fig. 3, but with the parts in a diierent position,and

Fig. an elevation, partly in section, of another modification.

Referring to the drawings, reference numeral I0 in Figs. l and 2indicates the barrel of a syringe having a plunger I I, a detachableneedlehub housing I2, a pressure-sealing and locking cap I3, and a plugI4 of brous material impregnated with antiseptic material.

In that form of the invention embodied in Figs. 1 and 2, the barrel Illmay be made of either glass or of a moldable plastic material, asstyrene, nylon, etc. The end to which the needle support is to beapplied has a narrow external band I5 of screw threads, while the otherend has a narrow band I6 of screw threads inside the barrel forengagement by threads on the plunger II. Externally of the barrel thereis a narrow annular flange I'I for engagement by the ngers of the userin making an injection.

The plunger II is of special construction in that it is a dual-hardnessrubber plunger, it being formed of natural rubber or synthetic rubbersuch as neoprene, of two different hardnesses. The head of the plunger,or that part of the plunger that has threads matching with those at IBon the barrel, and which threads are shown at I8, is semi-soft orrelatively soft rubber as indicated by the dotted shading, e. g., it maybe of a durometer around 50, while the stem portion is of harder rubber,that is inelastic and inflexible. The threads I8 are of an outerdiameter slightly greater than the inner diameter of the barrel. Thestem portion, i. e., that part extending to the right of the threadedhead in Figs. l and 2 is hard and inexible to insure against bending asthe head moves through the barrel, but the elastic threads I9 on thehead will iiatten somewhat, as shown in Fig. 2, as the head movesthrough the barrel, so as to insure that all material forwardly of theplunger will be forced out through the needle 20 as the head moves alongthe barrel. The head end moves evenly, without any erratic or jerkingaction, the complete contact of the elastic head with the inner wall ofthe barrel preventing any leakage backward about said head. Since theseveral threads on the head end engage the threads inside the barrel,the contents of the barrel are eiectively sealed inside the chamber ofthe syringe and the device may be stored indeiinitely withoutpossibility of injury by leakage of air or liquid into the chamber ofthe syringe. But the contents may be ejected completely and upon shortnotice, as hereinafter explained.

The needle hub or housing I2 is made of rubber or of a suitable plasticmaterial. and has a hypodermic needle 20 embedded in the hub andpermanently secured thereto. Threads at 2| on the hub engage those onthe barrel I0. A washer 22, of rubber or other impervious material, maybe inserted between the end of the barrel and the opposed face on thehub to prevent leakage or any contact of the contents of the syringewith the hub I2, as for example when the barrel is made of glass and thehub is made of material such as might react with the liquid in thechamber of the syringe. The needle extends through the washer tocommunicate with the chamber of barrel Il) and is permanently secured insaid hub I2, its inner end being flush with the inner face of washer 22.

The cap I3 may -be slipped on the hub I2, which has a shoulder at 23 forlimiting the movement of the annular flange of the cap in applying thesame to the reduced end of hub I2. Within this flange there is mounted aplug or mass I4 of fibrous material such as cotton, felt, cellulose orother material that will vabsorb and hold a uent antiseptic such as isacceptable for use in sterilizing a part of the body which is to beinjected with medicament. This plug has attached thereto in anyconvenient manner a thread 24, as by embedding the end of the thread inthe plug or by tying a vpart of the thread about the plug, or sewing itthrough the plug. It will be evident that upon removal of the cap, theplug can be drawn out of the cap suiciently to expose enough of it sothat it can be rubbed over the area to be treated, or the plug can -bepulled out of the cap entirely for greater convenience f the user, thethread preferably hanging out of the syringe so as to expose itslightly, as shown in Fig. 1.

The flanged end of the cap may consist of hard rubber or of othermaterial that can be threaded to engage threads on the needle hub, or itmay be elastic so that it can be expanded somewhat to engage resilientlyover the reduced end of the hub I2. I prefer, however, to make theflanged open end portion of rigid material while the part at 25 that isengageable by the end of the needle consists of soft resilient materialsuch as soft rubber, that can be flexed by the needle point to such anextent that the passage of the cannula is sealed vbut will spring backto place when the needle is withdrawn and such that the soft materialwill not be cut or damaged, while the passage in the needle will remainfully open and free to permit liquid to pass out when the cap isremoved.

As stated previously, this syringe comes completely assembled by themanufacturer to the user, for immediate action when ready. When a personis ready to use it, he does so as follows:

The syringe in its entirety is grasped in one hand. With the other hand,the cap is simply pulled off the hub I2. The cap is then inverted soythat its open end is over the area to be injected. The thread 24 isthen pulled gently which allows the plug I4 to emerge enough to do itspurpose. The entire cap I3 with its protruding plug I4 is held downwardtowards the injecting area and is then rubbed onto that area for aminute or so, thus sterilizing that area, as is properly prescribed fora needle injection. This being accomplished, the cap I3 with its plug I4is then discarded. The projecting needle is then inserted into thetissue by the usual standard technique. Before injecting, however, toavoid unforeseen results, care must be taken not to inject into a. bloodvessel directly. To be safe, proper and denite aspiration is necessary.With this syringe, such a move is accomplished with minute exactness,since the human element in moving the plunger at this point iseliminated. With the needle in place in the tissue, while one hand isgrasping the syringe barrel I0, the other hand merely gently rotates theplunger I I to the left a half a turn or so. This will cause a momentaryreduction in pressure within the barrel, and should the needle beentering into a vessel, that pressure reduction allows the counterpressure of the blood in that vessel to force a drop of blood back intothe barrel where it is seen by the operator. On seeing the presence ofblood, the operator then withdraws the syringe and inserts it into a newarea. Should the needle be in the proper tissue, the plunger is rotatedto the right a couple of turns which brings the elastic part of theplunger past the threads IS of the barrel, where it is able to movefreely. The operator then merely pushes the plunger with the thumb onthe thumb rest and the solution enters the tissue. The needle iswithdrawn, and the entire syringe discarded. In all other syringes,there is possibility of the plunger being forced out due to formation ofgas because of faulty medication or faulty filling. With my syringe,such a possibility is eliminated due to the threaded connection betweenparts. In all other syringes the operator must pull back on the plungerto aspirate, which sometimes tends to dislodge the needle from thetissue, since the needle was inserted by a push or a motion opposite tothat for aspirating. With my syringe, such a dislodgement is notpossible, unless done intentionally.

In the form of the invention shown in Figs. 3 and 4 the barrel 3l!contains a fluid medicament, and is attached to a plunger 3l by screwthreads. The stem is made of hard rubber or the like, but the head 32(or the threaded lportion of the plunger) consists of softer material ofsuch nature that the threads 33 that normally engage threads 34 on thebarrel will flatten as the plunger moves along the barrel after theplunger has been rotated to move the threads away from the coactingthreads on the barrel and so will eject all contents of the syringe. Thestem and head constitute a one-piece dual hardness plunger. Thus theliquid in the barrel is forced through the needle 35 if the cap 36 hasbeen removed from the plunger 3l. Until the cap has been so removed, thecontents of the chamber cannot leak out or be forced out by anythingless than destruction of the syringe nor can the barrel be removed fromthe plunger save by stripping the threads or unscrewing the barrel fromthe plunger. Obviously, the user of the syringe will insert two fingersunder the collar 37 on the plunger after removing the cap 35 and willthen press on the end 33 of the barrel with his thumb to make aninjection, the parts assuming a position as in Fig. 4 when the chamberis empty. In this form of the invention the cap may be formed asexplained for the cap in Figs. 3 and 4, with a soft resilient portion atthe region where the point of the needle contacts it, and with hardnessat the iiange, et cetera, as above explained, and the cap may containimpregnated brous material as in Figs. l and 2.

In the form of the invention shown in Fig. 5, the parts shown at SI',32', 33', 34' and 35' are or may be as in Figs. 3 and 4, but an annularflange 4U is formed on the outside of a mantle II that is integral withthe plunger 32. In this Way the flange 4t is brought up close to thethumb pressure member 42, so as to be easily engaged by the ngers of ahand whose thumb is on pressure member 42, thereby renderingmanipulation of the syringe easier.

In the manufacture of a dual-hardness plunger a mass of untreated rubberor like material may be placed in a mold and heat-treated, a lowerdegree of heat being applied to produce the semisoft head portion,whereas a higher degree of heat is applied to produce the relativelyhard, inexible stem portion, and the two different temperatures beingapplied simultaneously to the rubber in the same mold. It will beobvious that a a cap that consists of integral parts differing in suchqualities as hardness, flexibility and elasticity or extensibility.

The principal advantages secured by making a rubber member, such as aplunger of a syringe, in two integrally connected parts, one of which isrigid while the other is elastic and semi-soft are, rst, cheapness ofmanufacture and, second, saving in labor costs by elimination of stepsin assembling the syringes.

It will be understood that the head of the plunger need not necessarilyhave threads that engage threads inside the barrel. Thus, the plungermight have circumferential flanges or grooves of suitable diameter toact on the interior of the barrel so as to hold the parts againstrelative endwise movement and to scrape the inner wall of the barrel andremove all fluent material therefrom in the injecting operation, theinterior of the barrel being more or less smooth adjacent its open end.

It will be obvious to those skilled in the art that many changes may bemade in the devices herein disclosed, all without departing from thespirit of the invention; and therefore I do not limit myself to what isshown in the drawings and disclosed in the specification, but only asindicated in the appended claims.

This application is a continuation in part of my applications No.247,522, led September 20, 1951, now abandoned, and No. 255,983, ledNovember 13, 1951.

Having thus fully described my invention, what I claim is:

1. A hypodermic syringe comprising a barrel having a chamber to containa medicament, a needle communicating with the chamber, a plunger movableendwise relatively to said barrel, said barrel and said plunger havingshort bands of interengaging threads permitting a short relative endwisemovement by relative rotation of the barrel and plunger and theremainder of the adjacent center wall on at least one of said membersbeing smooth to permit free relative endwise movement of the barrel andplunger, and the threads on the other of said relatively movable partsbeing compressible to insure complete evacuation of said chamber upon afull stroke of said relatively movable parts.

2. A device as in claim 1, wherein the adjacent part of that part of themember carrying the compressible threads consists of relatively softmaterial and the remainder of said member consists of rigid, hardmaterial.

3. A device as in claim 2, wherein the plunger carries a mantle adaptedto encircle the barrel in one position of the relatively movable parts,and said mantle has a flange for engagement by a nger of the user whenhis thumb presses on the head end of the barrel.

4. A hypodermic syringe comprising a barrel, a hub of resilient materialscrew-threaded to one end of the barrel, a hypodermic needle embedded inthe hub, a narrow internal screw thread at the other end of the barrel,the remainder of the barrel having a smooth cylindrical inner surfaceand a plunger movable lengthwise of the barrel to force the contents ofthe syringe through said needle, said plunger having a narrow externalband of screw threads at its forward end adapted to engage the threadsof the barrel, said plunger being freely movable through the remaininglength of the barrel after said threads are disengaged by relativerotation of the plunger and barrel.

5. A syringe as in claim 4, wherein the screw threads on the plunger areof greater outer diameter than the inner diameter of the cylindricalportion of the barrel and are of compressible material, so as to becapable of flattening against the inner periphery of the barrel as theymove along the smooth cylindrical inner surface of the same.

6. A device as in claim 4, wherein the head of the plunger is ofcompressible material while the stem is rigid, the threads being formedon the head and being of slightly greater outer diameter than the innerperiphery of the smooth part of the barrel so that they can flatten soas to scrape the inner peripheral face of such smooth part of thebarrel.

7. A device as in claim 6, wherein the threads consist of rubber.

8. In a hypodermic syringe, a threaded barrel, a threaded hub affixed tosaid barrel, a hollow needle embedded in the hub in position tocommunicate with the interior of the barrel when the hub is screwed tothe barrel, the hub having a reduced extension providing a shoulder, andthe syringe including a cap fitting on the shoulder, a plug of fibrousmaterial ntting in the cap, said plug being impregna-ted with antisepticmaterial.

9. A device as in claim 8, including a length of thread secured to theplug and protruding from the cap, for the purpose set forth.

References Cited in the rile of this patent UNITED STATES PATENTS NumberName Date 1,718,602 Smith June 25, 1929 2,551,339 Ryan May 1, 1951FOREIGN PATENTS Number Country Date 182,531 Switzerland Feb. 15, 1936480,166 Canada l Jan. 15, 1952 957,829 France Aug. 29, 1949

